1. Field of the Invention
The invention relates to a preform and method for making the same, particularly, to a carbon nanotube composite preform and a method for making the same.
2. Discussion of Related Art
Carbon nanotubes (CNT) are a novel carbonaceous material and received a great deal of interest since the early 1990s. Carbon nanotubes have interesting and potentially useful electrical and mechanical properties. Due to these and other properties, it becomes an important application direction for CNTs to be used as fillers in engineering materials.
Nowadays, the method for growing a CNT array on a substrate, such as a glass, silicon, or heat-resistant metal substrate has matured. CNT arrays are in widespread use, such as in field emission tubes, ultra-thin flat panel displays, cathode electrodes, biosensors and so on.
However, naturally occurring gas-filled spaces between CNTs in CNT arrays lead to poor radial properties (such as thermal conductivity) and thus affect the properties of the whole material. So it is beneficial to fill gaps between CNTs in the CNT array with metals or polymer materials to make a composite material. This ensures the composite material has improved radial properties.
Conventionally, the CNT composite material is made by directly infiltrating the melting metal or polymer material into the CNT array. Referring to an article by H. Huang entitled “Aligned Carbon Nanotube Composite Films for Thermal Management” (Adv Mater., Vol 17, 2005, p 1652), the above-described manufacturing process is reported. However, the gaps between the CNTs in the CNT array are so small that some materials, such as indium, copper, etc., cannot infiltrate the CNT array well.
What is needed, therefore, is a CNT composite preform with filterable gaps between CNTs and a simple, low cost, and short cycle method for making the described CNT composite preform.